Of course you do. And this killer combo is the fastest, easiest way to ensure you're accurate to the yard. Let's start with the revolutionary Speed Dial. No more guessing. No more "gapping". From 20 to 80 yards, you're dialed in, no matter what sort of crossbow you use. Calibrate (with your scope) from 20 yards, then calibrate from 60, and you're honed-in for the hunt. The Speed Dial comes with 48 different calibrated yardage tapes for bow speeds of 260 to 410 F.P.S. And install? Easy. Piggybacks on any standard 7/ 8 " Weaver®-style rail with 2-pins... 30 seconds later, you're ready to calibrate! Better yet, the Speed Dial adds minimal height and weight to your set up. Rock solid CNC machined aluminum mount weighs just 7 ozs.